Deformation caused by the 2011 eastern Japan great earthquake monitored using the GPS single-epoch precise point positioning technique

Crustal deformation can provide constraints for studying earthquake rupture and shock wave transmission for the Mw9.0 eastern Japan great earthquake. Using the single- epoch precise point positioning （PPP） method and the appropriate positioning flow, we process GPS data from six IGS （International GNSS Service） sites （e.g., MIZU, TSK2, USUD, MTKA, AIRA and KSMV） located in Japan and obtain the positioning results with centimeter scale precision. The displacement time series of the six sites are analyzed using the least squares spectral analysis method to estimate deformations caused by the Mw9.0 mainshock and the Mw7.9 aftershock, and the cumulative displacements after 1 day. Mainshock displacements at station MIZU, the nearest site to the mainshock in the North （N）, East （E）, and Up （U） directions, are -1.202 m, 2.180 m and -0.104 m, respectively, and the cumulative deformations after 1 day are -1.117 m, 2.071 m and -0.072 m, respectively. The displacements at station KSMV, the nearest site to the Mw7.9 aftershock in the N, E and U directions, are -0.032 m, 0.742 m and -0.345 m, respectively. The other sites obviously experienced eastern movements and subsidence. The deformation vectors indicate that the horizontal displacements caused by the earthquake point to the epicenter and rupture. Elastic bounds evidently took place at all sites. The results indicate that the crustal movements and earthquake were part of a megathrust caused by the Pacific Plate sinking under the North American Plate to the northeast of Japan island arc.

Integrity monitoring scheme for single-epoch GNSS PPP-RTK positioning

Integrity monitoring for precise point positioning is critical for safety-related applications.With the increasing demands of high-accuracy autonomous navigation for unmanned ground and aerial vehicles,the integrity monitoring method of high-precision positioning has become an essential requirement.While high precision Global Navigation Satellite Systems(GNSS)positioning is widely used in such applications,there are still many difculties in the integrity monitoring method for the multi-frequency multi-GNSS undiferenced and uncombined Precise Point Positioning(PPP).The main difculties are caused by using the measurements of multiple epochs in PPP.Based on the baseline Multiple Hypothesis Solution Separation(MHSS)Advanced Receiver Autonomous Integrity Monitoring(ARAIM)algorithm,this paper discusses the feasibility of the pseudorange-based baseline ARAIM method on the single-epoch PPP based on Real-Time Kinematic(RTK)networks(PPP-RTK)framework to overcome these difculties.In addition,a new scheme is proposed to transfer the conventional PPP process into the single-epoch PPP-RTK framework.The simulation results using the proposed model are analyzed in this study.The Protection Levels(PLs)estimated by PPP Wide-lane Ambiguity Resolution(PPP-WAR)model with regional corrections can reach the meter level and the PLs estimated by PPP Ambiguity Resolution(PPP-AR)and PPP-RTK models are usually the sub-meter level.Given a horizontal Alert Limit(AL)of 1.5 m,the global coverage of availability above 99.9%for PPP-WAR,PPP-AR,and PPP-RTK can reach 92.6%,99.4%,and 99.7%respectively.The results using real kinematic data also show that tight PLs can be achieved when the observation conditions are good.